feat: support taproot addresses

[gregdhill]

Signed-off-by: Gregory Hill [email protected]

Some initial draft code for supporting taproot spending. As noted in #606, it is not possible to determine the "address" from a key path spending transaction alone since Schnorr signatures do not support public key recovery. Therefore to verify that a P2TR spend is valid we must provide the spent TransactionOutput when reporting a theft here. Since #603 is merged, we do not explicitly require that inputs to issue, redeem, refund and replace transactions are valid since they only need to verify the output. The benefit of this approach is also to disambiguate witness parsing, we currently assume all non-standard inputs are P2WSH - see this comment.

EDIT: since theft reporting was removed the problem described above is no longer a concern - P2TR addresses can be plainly parsed from the scriptPubKey outputs. Updated the PR to add Address::P2TRv1(tweaked_pub_key) so taproot addresses can be used throughout the runtime.

Closes #606

References

• IsWitnessStandard
• SignatureHashSchnorr
• BIP 340
• BIP 341